Distribution of Phippsia algida and Autosuccession in the Polar Semidesert, Canadian High Arctic

Abstract

Extensive areas of Phippsia algida-dominated communities are common in the Canadian High Arctic. The data presented here describe maintenance of these communities via autosuccession. A correlation between growth stage and plant age was developed for this species. Characteristics of the population of plants within each growth stage were used as “snapshots” to illustrate changes in plant to plant relationships through time. Although bare soil and moss were equally available as substrates in the landscape, seed rain was highest on bare soil (90%), in close proximity to a mature Phippsia plant. Germination was low but similar in moss and bare soil microsites. Survival from seedling to reproductive age was not associated with substrate type. Mortality occurred within early growth stages due to proximity to other young plants of Phippsia, but proximity to a mature Phippsia plant was not deleterious. Microsuccession occurred within a large plant clump, but individual replacement appeared to be largely conspecific (autosuccession). Although this species reproduces entirely by seed, the demographic consequence of its dispersal is similar to cloning: high density of conspecific shoots with a high probability of relatedness, with large gaps between clumps. The population age structure of this species appears to reflect surficial disturbance patterns. In areas of minor disturbance, population age structure appears to reflect a period of exceptionally low (1969 ± 4 yr) and high (1962) July mean temperature.